A ganglion (plural: ganglia) is a group of neuronal cell bodies and processes located in the peripheral nervous system 1.
Ganglia can be categorized into two groups - sensory ganglia and autonomic ganglia. Sensory ganglia primarily contain the cell bodies of neurons as well as their central and peripheral processes leading from these cell bodies, whereas autonomic ganglia primarily contain the connections of preganglionic neurons to the cell bodies of post ganglionic neurons 1,2.
The sensory ganglia include the dorsal root ganglia of the spine and the ganglia in the sensory roots of the trigeminal, facial, vestibulocochlear, glossopharyngeal, and vagal cranial nerves 1.The autonomic ganglia can be divided into the ganglia of the sympathetic nervous system including the prevertebral ganglia and paravertebral sympathetic ganglia (sympathetic chain), the parasympathetic nervous system ganglia, and the ganglia of the enteric nervous system 1.
Ganglia are encapsulated by fibrous connective tissue, except for the enteric nervous system ganglia which resemble central nervous system nuclei and do not have the connective tissue capsule 1,2. Note that an equivalent grouping of neuronal cell bodies in the central nervous system is referred to as a nucleus (plural: nuclei), which is why the basal ganglia are also called the “basal nuclei”, however, the term basal ganglia is still more commonly used.